African-American women are more likely found at advanced stage and therefore have a worse survival. While the poor outcome observed in African-American women with breast cancer may be multifactorial, the aggressiveness of their disease may have a biological base. A significant tumor shrinkage induced by preoperative chemotherapy may be used as a surrogate marker to predict patient's survival outcome. We hypothesize that: (1) the differentially expressed proteins of each breast cancer predict tumor response to the preoperative chemotherapy; and (2) the biomarkers characterizing resistance to the treatment are more common in African-American women with locally advanced cancer than Caucasian Americans. Accordingly, this study will search for novel specific proteins in breast cancer that predict tumor responses to preoperative chemotherapy. The chemical identities of these proteins will be determined by mass spectrometry/proteomics. In addition, whether the "drug-resistant" biomarkers are more common in African-American women will be systematically compared with the Caucasian American women. Finally, the prognostic value of the biomarkers will be compared with the conventional parameters such as patients' demographic and tumor features in a multivariant analysis to determine their independent predicative value and interaction of various factors. [unreadable] [unreadable] A new technology, SELDI or Surface-Enhanced Laser Desorption/lonization mass spectrometry will be used to discover biomarkers that can predict response of breast cancer to preoperative chemotherapy. The identities of these biomarkers will be established by spectrometry/proteomic of fragments of biomarkers. By completion of this project, prognosticators characterizing tumor response to the preoperative chemotherapy will be identified to better classify locally advanced breast cancer. The aggressive nature of the disease in African-Americans reflected by the proteomic markers characterizing tumor response to drug treatment will be objectively compared to Caucasians with comparable stage of diseases and identical treatment.